In recent years, the silicon photonics technology has been developed. A silicon photonics technique has been developed. The silicon photonics technique is a connection technique between an optical device and an electronic device by using an optical circuit which is made of silicon as a material and which uses an optical waveguide. A semiconductor device on which the optical device and the electronic device connected by using the optical circuit as described above is mounted is referred to as an optical communication module.
Such semiconductor devices include a semiconductor device including an optical waveguide which serves as an optical signal transmission line and which is made of a semiconductor layer formed on a basic body via an insulating layer, and having an insulating film formed to cover the optical waveguide. In this case, the optical waveguide functions as a core layer, and the insulating layer and insulating film function as clad layers.
Japanese Patent Application Laid-Open Publication No. 2012-27198 (Patent Document 1) discloses an optical semiconductor device having a semiconductor layer of an intrinsic semiconductor formed on a substrate and having an optical waveguide making up a part of the semiconductor layer.